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Mechanisms of Shell Egg Deterioration: Comparisons of Chicken and Duck Eggs1,2
LYSINE AND PROTEIN REQUIREMENTS OF TURKEYS
Supplementation of poult diets with lysine. Poultry Sci. 33 : 1280-1282. Kratzer, F. H., P. N. Davis and B. J. Marshall, 1955. Cottonseed meal in rations for starting poults, growing turkeys and turkey breeder hens. Poultry Sci. 34: 462-468. Kratzer, F. H., P. N. Davis and B. J. Marshall, 1956. The protein and lysine requirements of turkeys at various ages. Poultry Sci. 35: 197202. Yacowitz, H., R. D. Carter, J. Wyne and M. G. McCartney, 1956. Effects of varying protein and fat levels in a finishing ration for turkey broilers. Poultry Sci. 35: 227-229.
Mechanisms of Shell Egg Deterioration: Comparisons of Chicken and Duck Eggs 12 MARVIN
B.
R H O D E S AND ROBERT E.
FEENEY
Department of Biochemistry and Nutrition, College of Agriculture, University of Nebraska, Lincoln, Nebraska (Received for publication March 20, 1957)
INTRODUCTION
to a basic understanding ONEof approach biological systems is through a comparative study of the physical and biochemical properties of closely related species. It is the purpose of such studies to utilize the subtle differences provided by nature to determine the relative significances and roles of the individual components of the systems. An attempt has been made to utilize such an approach in the present investigation. A comparative study of certain properties of chicken and duck eggs has been made in order to obtain information basic to the understanding of the causes and mechanisms of the deteriora1
Published with the approval of the Director as Paper 808, Journal Series, Nebraska Agricultural Experiment Station. 2 This work supported in part by RMA funds through the Regional Research Project under the NCM-7 Technical Committee.
tions of quality of chicken eggs during storage. Chicken and duck eggs have been reported to have closely similar compositions. Chemically, they apparently differ primarily in the relative amounts of their various constituents and in minor (but important) differences in the molecular structure of the individual components. Most of the information available on this subject refers to the egg whites. Bain and Deutsch (1947) in an electrophoretic study found important differences in the ovalbumin, conalbumin and lysozyme contents. These differences were confirmed by means of chemical and biochemical analyses by MacDonnell, Ducay, Sugihara and Feeney (1954) who also reported a significant difference in the content of ovomucoid and in the nature of the sulfhydryl groups. In a further study, Sugihara, MacDonnell, Knight and Feeney (1955) found large differences in the contents of virus antihemagglutinin activity
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J. R. Couch, 1956. The effect of amino acid supplements to the diet of Broad Breasted Bronze turkey poults fed various levels of protein and productive energy. Poultry Sci. 35: 1069-1073. Fisher, H., J. Dowling, Jr. and K. H. Maddy, 1956. Low protein diets for turkeys raised under practical conditions. Poultry Sci. 35: 239241. Heady, E. O., S. Balloun and G. W. Dean, 1956. Least-cost rations and optimum marketing weights for turkeys. Iowa Agr. Exp. Sta. Res. Bui. 443. Klain, G. J., D. C. Hill and S. J. Slinger, 1954.
891
892
#
M. B. RHODES AND R. E. FEENEY
MATERIALS AND METHODS
The chicken eggs used in this study were produced on the University farm and were large Grade AA. The duck (Pekin) eggs were ungraded white eggs obtained from two different farms in the immediate area. Experiments in which the unbroken shell eggs were incubated were conducted as recently described (Feeney et al., 1956). In the experiments in which the influence of ammonia gas was determined, all the eggs were placed in 10 inch desiccators. They were divided into mixed lots of duck eggs and chicken eggs so as to insure a uniformity of exposure. The atmosphere of ammonia was obtained by the addition of 2 ml. of ammonium hydroxide (28% NH 3 ) to each desiccator. The white and yolk indices were determined according to Heiman and Carver (1936) and Wolk, McNally and Brant (1952) respectively. The general techniques for the aseptic separation and recombination of the yolks and whites were as previously described by Feeney, Silva and MacDonnell (1951).
Treatment of the intact and broken out egg constituents with reducing chemicals was performed according to MacDonnell, Lineweaver and Feeney (1951). The determinations of the turbidities of diluted egg white solutions were performed as follows: The egg white was blended according to Sugihara et al. (1955) and thoroughly mixed with 5 volumes of distilled water. The mixture was allowed to stand approximately 5 minutes and turbidity then determined in a photoelectric colorimeter (Klett). The lysozyme employed in this work was prepared by direct crystallization from egg white and further purified by two recrystallizations and an isoelectric precipitation (Alderton and Fevold, 1946). It was dissolved in dilute acetic acid and then the pH of the solution was raised to 8.5 with sodium hydroxide before use. Conalbumin was prepared in crystalline form according to Feeney and Rhodes (1956). t RESULTS
Comparative deteriorations of chicken and duck eggs on incubation at 37° and 44° C: The changes in white and yolk indices in chicken and duck eggs were determined after storage at 37° and 44°C. Experiments were performed over a six-month period with small numbers of eggs from different sources. In all cases the duck eggs were found extremely resistant to deterioration at these temperatures as compared with the rapid changes observed in the chicken eggs. There was no detectable deterioration in the duck eggs at 37° and only a slight deterioration even after four days at 44°. Table 1 contains the data of five different experiments at 44°. The amounts and rates of deteriorations of chicken eggs were similar to those recently reported (Feeney, Weaver, Jones and Rhodes, 1956). Effect of storage of egg yolks in blended
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(inhibition of hemagglutination caused by influenza virus and certain other viruses). A summarization of the comparative data of MacDonnell et al. (1954) and Sugihara et al. (1955) gives the following percentage composition on a dry weight basis for the chicken and duck egg whites respectively: lysozyme, 3.5 and 0.90; conalbumin, 12 and 2.8; ovomucoid, 11 and 15; cysteine (native), 0.46 and 0.30; cysteine (denatured), 0.60 and 0.32. The chicken egg white contained approximately 50% more virus antihemagglutinin activity. There are, of course, other differences in the poorly characterized components such as globulins and avidin, and Romanoff (1943) has reported differences in the physicochemical properties of the various layers of the egg white.
m
893
CHICKEN AND DUCK EGG DETERIORATION TABLE 1. —Deterioration
Exp.
of chicken and duck eggs
Chicken eggs1
Storage conditions
Duck eggs1
Indices Yolk
8.7 9.5
0.056 0.048
0.42 0.23
4 2
3 4
8.9 9.4
0.074 0.075
0.47 0.31
94 94
3 3
9.0 9.4
0.072 0.024
2 44 44
97 49 97
4 4 4
9.0 9.6 9.7
44 44
0 46 98
24 22 23
8.7 9.4 9.5
Temp.
Time
A
°C. 2 44
hr. 48 48
6 6
B
2 44
48 48
C
2 44
D
E
pH
Indices pH White
Yolk
8.7 9.5
0.074 0.083
0.45 0.41
6 6
9.0 9.4
0.078 0.082
0.40 0.36
0.44 0.16
2 3
9.0 9.4
0.057 0.053
0.40 0.37
0.062 0.051 0.027
0.42 0.23 0.14
4 4 4
8.9 9.5 9.6
0.079 0.072 0.061
0.46 0.40 0.38
0.064 0.043 <0.02
0.44 0.22 0.17
18
8.5
0.077
0.41
13
9.4
0.088
0.38
1
Values given for pH and indices are averages of data of numbers of eggs indicated. The five different experiments were performed over a period of four months.
•
white: Egg yolks of each species were separated aseptically from the whites and laced in bottles containing blended white of the same species and in other bottles containing white of the other species. In three separate experiments in which duck yolks were suspended in chicken egg white, little or no deterioration occurred under storage conditions which caused a rapid deterioration of chicken yolks (as measured by the change in yolk index). The results of one experiment in which the various combinations were studied are given in Table 2. Influence of reducing chemicals: Comparative studies were made on the influence of reducing chemicals (MacDonnell et al., 1951). In all cases closely parallel results were obtained with both the duck and chicken eggs and their components. Thioglycol caused thinning of the thick egg white, weakening of the yolk membrane and dissolution of preparations of yolk membranes of the eggs of both species in a similar manner. Effect oj ammonia: In contrast to the
nearly identical results with the two species given by reducing chemicals as described above, the effects of ammonia were radically different. As previously described by others (Almquist, Givens and Klose, 1934; Cotterill and Nordskog, 1954) exposure of intact shell eggs to ammonia gas caused decreases in the white index and increased translucence of the egg white. In the present studies decreases in the yolk indices were also obtained. There were, however, TABLE 2.—Deterioration of separated yolks stored in different blended whites1 Combinations
Yolk Indices 2
Yolk
White
Control 3
Stored4
Chicken Chicken
Chicken Duck
0.42 0.41
0.26 0.20
Duck Duck
Chicken Duck
0.41 0.38
0.38 0.36
1 Separated, combined and stored as described by Feeney el al. (1951). 2 Five replicates in each lot. 3 Controls measured 2 to 3 hours after combination. 4 Stored at 44°C. for 66 hours.
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White
No. eggs
No. eggs
894
M. B. RHODES AND R. E. FEENEY TABLE 3.—Effects
Chicken eggs1
Storage conditions Exp. NH82
+ B
0
+ C
0
+ 1 2
Duck eggs1
Indices
No. eggs
PH
White
Yolk
No. eggs
Indices PH
White
Yolk
°C. 2 37 37
hr. 24 24 24
6 6 6
9.1 9.1 9.5
0.055 0.046 0.037
0.42 0.37 0.30
6 8 8
9.2 9.1 9.5
0.062 0.057 0.064
0.41 0.38 0.38
37 37
24 24
6 6
9.2 9.5
0.055 0.038
0.41 0.34
8 8
9.2 9.5
0.073 0.077
0.41 0.42
2 2
24 24
6 6
8.9 9.6
0.063 0.066
0.42 0.40
Figures given for pH and indices are averages of data of number of eggs indicated. Ammonia gas added to desiccators as described in text. 0 = n o addition; -(- = addition.
no detectable differences in either the white with ammonia, other alkaline materials and or yolk indices in the duck eggs treated reducing chemicals markedly decreased the under similar conditions. Careful deter- turbidities obtained on dilution. Dilution in minations of changes in pH values of the solutions of relatively high salt concentraegg whites proved that the different results tion also decreased the turbidity. obtained with the chicken and duck eggs In Figure 1 are plotted the turbidities obwere not due to differences in final pH. The tained when blended chicken and duck egg data from three of a series of experiments white were mixed in various proportions on this subject are presented in Table 3. and then diluted with 5 volumes of water. Both chicken and duck egg yolks showed It is readily seen that the amount of turthe glossy effect described by Cotterill and bidity obtained is directly proportional to Nordskog (1954) for chicken eggs. the relative amount of chicken egg white Effect of dilution of egg white on forma- present in the mixture. tion of turbidity: The chicken and duck Influence of lysozyme on turbidity of egg whites differed extensively in the tur- duck egg white on dilution: Among the bidities obtained upon dilution in water. various differences between the whites of The procedure adopted for this study was the two species, one of more pertinence to rather similar to one of the older procedures the problem at hand was the difference in for the determination and separation of lysozyme content. It was knowledge of this crude ovomucin from egg white (Young, difference that made possible the prepara1937). Unblended chicken egg white gave tion of high-volume angel food cakes with a white web-like thick precipitate when duck egg whites through the addition of a mixed with S volumes of distilled water, small amount of lysozyme (MacDonnell, while duck egg white gave only a small Feeney, Hanson, Campbell and Sugihara, transparent gelatinous precipitate. When 19SS). the experiments were performed with Experiments were therefore performed in blended egg whites, chicken egg whites gave which crystalline lysozyme prepared from very turbid suspensions and the duck whites chicken egg white was added to duck egg only a slight opalescence. white and the influence of such additions Pre-treatment of the chicken egg white on the turbidities obtained on dilution were
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A
0 0
Temp. Time
of ammonia gas on chicken and duck eggs
CHICKEN AND DUCK EGG DETERIOKATION
FIG. 1. Influence of percentage composition of mixtures of chicken and duck white on the turbidity obtained on dilution in water. Turbidity was produced by dilution with 5 volumes of water as described in text.
studied (Figure 2). From the data of Figure 2 it is evident that the addition of very small amounts of lysozyme causes increases in the turbidities of duck egg whites upon dilution in water. No increases in turbidities were obtained by addition of conalbumin in amounts equivalent to the difference in the composition of duck and chicken white. DISCUSSION In the comparative studies of the storage stabilities of the chicken and duck eggs, a relatively high stability of the duck eggs was found in the resistance of the yolk membrane to deteriorative weakening as well as in the resistance of the thick egg white to thinning. A similar difference in the stability of both of the structures was
/ 2 3 f LYSOZYME ADDED Cmg/m/)
FIG. 2. Influence of addition of graded levels of lysozyme to duck white on the turbidity obtained on dilution in water. Turbidity was produced by dilution with 5 volumes of water as described in text. A blank consisting of equivalent amounts of lysozyme diluted in water was subtracted from each reading. (The blank reading subtracted was only 8-12 percent of the total.)
to have been anticipated from the proposal of Feeney et al. (1956) that the storage thinnings of the yolk membrane and thick white of the chicken egg have a similar basic mechanism. The chicken and duck eggs were found to differ in two other important respects: The chicken eggs showed deteriorations when exposed to ammonia gas and the chicken egg white produced a high turbidity on dilution in water. The duck eggs showed neither of these effects. The first of these differences might indicate a much greater lability of the principal structural component in chicken eggs to the alkalinity of the ammonium ion. Both of these differ-
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PERCENT, CHICKEN E66 WHITE , t'o go f« io 4 PERCENT PUCK 666 WHITE
895
896
M. B. RHODES AND R. E. FEENEY
duck egg white (MacDonnell et al., 1954) might be responsible for the resistance to a deteriorative mechanism involving reduction. On the other hand, the very low amount of lysozyme in the duck egg white might be responsible for resistance to a deteriorative mechanism involving changes in complexes of the proteins. The present data could be considered as more strongly supporting the theory involving the solubility of complexes. Many other aspects, however, remain to be investigated. Of major significance should be studies of the physical and chemical properties of the important constituents of duck egg white and analyses of the minor constituents such as anions, nucleic acids and globulins. Such studies on the comparative biochemistry should obviously be extended to include eggs of other avian species. SUMMARY AND CONCLUSIONS
In a study of the comparative proper" ties of chicken and duck eggs, the following results were obtained: 1. The duck eggs were much more resistant on storage to the deteriorative thinning of the thick egg white and weakening of the yolk membrane. In the case of the yolks, the chicken eggs deteriorated at least eight times faster than the duck eggs. 2. The egg white of one species did not influence the rate of breakdown of the yolk of the other species. 3. Reducing chemicals thinned the whites and yolk membranes of both species in a similar manner. 4. Duck egg white differed from chicken egg white in that blended duck egg white did not produce a high turbidity on dilution with water as was the case with chicken egg white. 5. Duck eggs differed from chicken eggs
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ences might indicate a difference in the type and extent of the interaction of constituents in complex formation. The possibility that lysozyme might be involved was strongly supported by the observations in which the addition of lysozyme to duck egg white caused turbidities on dilution similar to those obtained on dilution of chicken egg white. The apparent inertness of the duck egg white insofar as contributing to the turbidities of diluted mixtures with chicken egg white (or vice versa), however, suggested that both the reactivities and the stoichiometric relationships of the constituents should be considered. On the other hand, reducing chemicals had similar effects on the eggs of both species. This suggested a close similarity in the properties and composition of their important structural constituent (s). If one accepts the proposal of Feeney et al. (1956), that the deterioration of the yolk membrane and thick egg white have a similar basic mechanism, certain conclusions may be drawn from the results of the experiments in which the yolks were stored in the blended whites. The results with the duck egg yolks in chicken white might indicate that the chicken egg white does not contain an excess of a material which causes the deterioration (and which is diffusible). Likewise, the results with the chicken egg yolks in the duck white might indicate that the duck white does not contain an excess of an inhibitor or stabilizer (and which is diffusible). The results of the present study are in agreement with both of two possible theories for the mechanisms of storage thinning of egg white and yolk membrane: chemical reduction (MacDonnell et al., 1951) and, changes in solubility of complex structures (Hawthorne, 1950; Feeney et al., 1952; and Cotterill and Winter, 1955). The apparently low amount of sulfhydryl in
•
CHICKEN AND DUCK EGG DETERIORATION
REFERENCES Alderton, G., and H. L. Fevold, 1946. Direct crystallization of lysozyme from egg white and some crystalline salts of lysozyme. J. Biol. Chem. 164:1-5. Almquist, H. J., J. W. Givens and A. Klose, 1934. Transmission of light by egg albumen. Ind. Eng. Chem. 26: 847. Bain, J. A., and H. F. Deutsch, 1947. The electrophoretic study of egg white proteins of various birds. J. Biol. Chem. 171: 531-541. Cotterill, O. J., and A. W. Nordskog, 1954. Influence of ammonia on egg white quality. Poultry Sci. 3 3 : 432-434. Cotterill, O. J., and A. R. Winter, 1955. Egg white lysozyme. 3. The effect of pH on the lysozyme-ovomucin interaction. Poultry Sci. 34: 679-686. Feeney, R. E., E. D. Ducay, R. B. Silva and L. R. MacDonnell, 1952. Chemistry of shell egg deterioration: The egg white proteins. Poultry Sci. 3 1 : 639-647. Feeney, R. E., and M. B. Rhodes, 1956. Prepa-
ration and antimicrobial activity of crystalline conalbumin. Federation Proc. 15: 249-250. Feeney, R. E., R. B. Silva and L. R. MacDonnell, 1951. Chemistry of shell egg deterioration: The deterioration of separated components. Poultry Sci. 30: 645-650. Feeney, R. E., J. M. Weaver, J. R. Jones and M. B. Rhodes, 1956. Studies of the kinetics and mechanism of yolk deterioration in shell eggs. Poultry Sci. 35: 1061-1066. Hawthorne, J. R., 1950. The action of egg white lysozyme on ovomucoid and ovomucin. Biochim. Biophys. Acta, 6: 28-35. Heiman, V., and J. S. Carver, 1936. The albumen index as a physical measurement of observed egg quality. U. S. Egg Poultry Mag. 42: 426429. MacDonnell, L. R., E. D. Ducay, T. F. Sugihara and R. E. Feeney, 1954. Proteins of chicken, duck, and turkey egg white. Biochim. Biophys. Acta, 13: 140. MacDonnell, L. R., R. E. Feeney, H. L. Hanson, A. Campbell and T. F. Sugihara, 1955. The functional properties of the egg white proteins. Food Tech. 9:49-53. MacDonnell, L. R., H. Lineweaver and R. E. Feeney, 1951. Chemistry of shell egg deterioration: The effects of reducing agents. Poultry Sci. 30: 856-863. Romanoff, A. L. 1943. Differentiation in layers of avian albumen. Food Res. 8: 286-291. Sugihara, T. F., L. R. MacDonnell, C. A. Knight and R. E. Feeney, 1955. Virus antihemagglutinin activity of avian egg components. Biochim. Biophys. Acta, 16: 404-409. Wolk, J., E. H. McNally and A. W. Brant, 1952. Yolk measurements used as an indicator of temperature deterioration of eggs. Poultry Sci. 31: 586-588. Young, E. G., 1937. On the separation and characterization of the proteins of egg white. J. Biol. Chem. 120: 1-9.
NEWS AND NOTES (Continued from page 870) in 1891 and obtained a B.S. degree at the University of Wisconsin in 1915. From 1915 to 1916 he served as Assistant Poultry Husbandman at Kansas State College, and from 1916 to 1917 as Instructor in Poultry Husbandry at the University of Wisconsin. In 1917 he joined the staff of the University of Nebraska.
He is a member of the Poultry Science Association, having served as Associate Editor of Poultry Science from 1933 to 1938 and the American Association for the Advancement of Science. Dr. John L. Adams will succeed him as Head of the Department. Professor Adams was born in Manitou, Oklahoma in 1921 and obtained a B.S.
(Continued on page 917)
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in that ammonia gas did not cause duck eggs to deteriorate rapidly as was the case with chicken eggs. Exposure of chicken eggs to ammonia gas resulted in an extensive decrease in the turbidity obtained on dilution of the white. 6. When chicken-egg-white lysozyme was added to duck egg white prior to dilution, duck egg white gave a high turbidity on dilution similar to chicken egg white. The significance of these findings in understanding the causes and mechanisms of deterioration of egg quality on storage was discussed.
897
Supplementation of poult diets with lysine. Poultry Sci. 33 : 1280-1282. Kratzer, F. H., P. N. Davis and B. J. Marshall, 1955. Cottonseed meal in rations for starting poults, growing turkeys and turkey breeder hens. Poultry Sci. 34: 462-468. Kratzer, F. H., P. N. Davis and B. J. Marshall, 1956. The protein and lysine requirements of turkeys at various ages. Poultry Sci. 35: 197202. Yacowitz, H., R. D. Carter, J. Wyne and M. G. McCartney, 1956. Effects of varying protein and fat levels in a finishing ration for turkey broilers. Poultry Sci. 35: 227-229.
Mechanisms of Shell Egg Deterioration: Comparisons of Chicken and Duck Eggs 12 MARVIN
B.
R H O D E S AND ROBERT E.
FEENEY
Department of Biochemistry and Nutrition, College of Agriculture, University of Nebraska, Lincoln, Nebraska (Received for publication March 20, 1957)
INTRODUCTION
to a basic understanding ONEof approach biological systems is through a comparative study of the physical and biochemical properties of closely related species. It is the purpose of such studies to utilize the subtle differences provided by nature to determine the relative significances and roles of the individual components of the systems. An attempt has been made to utilize such an approach in the present investigation. A comparative study of certain properties of chicken and duck eggs has been made in order to obtain information basic to the understanding of the causes and mechanisms of the deteriora1
Published with the approval of the Director as Paper 808, Journal Series, Nebraska Agricultural Experiment Station. 2 This work supported in part by RMA funds through the Regional Research Project under the NCM-7 Technical Committee.
tions of quality of chicken eggs during storage. Chicken and duck eggs have been reported to have closely similar compositions. Chemically, they apparently differ primarily in the relative amounts of their various constituents and in minor (but important) differences in the molecular structure of the individual components. Most of the information available on this subject refers to the egg whites. Bain and Deutsch (1947) in an electrophoretic study found important differences in the ovalbumin, conalbumin and lysozyme contents. These differences were confirmed by means of chemical and biochemical analyses by MacDonnell, Ducay, Sugihara and Feeney (1954) who also reported a significant difference in the content of ovomucoid and in the nature of the sulfhydryl groups. In a further study, Sugihara, MacDonnell, Knight and Feeney (1955) found large differences in the contents of virus antihemagglutinin activity
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 22, 2015
J. R. Couch, 1956. The effect of amino acid supplements to the diet of Broad Breasted Bronze turkey poults fed various levels of protein and productive energy. Poultry Sci. 35: 1069-1073. Fisher, H., J. Dowling, Jr. and K. H. Maddy, 1956. Low protein diets for turkeys raised under practical conditions. Poultry Sci. 35: 239241. Heady, E. O., S. Balloun and G. W. Dean, 1956. Least-cost rations and optimum marketing weights for turkeys. Iowa Agr. Exp. Sta. Res. Bui. 443. Klain, G. J., D. C. Hill and S. J. Slinger, 1954.
891
892
#
M. B. RHODES AND R. E. FEENEY
MATERIALS AND METHODS
The chicken eggs used in this study were produced on the University farm and were large Grade AA. The duck (Pekin) eggs were ungraded white eggs obtained from two different farms in the immediate area. Experiments in which the unbroken shell eggs were incubated were conducted as recently described (Feeney et al., 1956). In the experiments in which the influence of ammonia gas was determined, all the eggs were placed in 10 inch desiccators. They were divided into mixed lots of duck eggs and chicken eggs so as to insure a uniformity of exposure. The atmosphere of ammonia was obtained by the addition of 2 ml. of ammonium hydroxide (28% NH 3 ) to each desiccator. The white and yolk indices were determined according to Heiman and Carver (1936) and Wolk, McNally and Brant (1952) respectively. The general techniques for the aseptic separation and recombination of the yolks and whites were as previously described by Feeney, Silva and MacDonnell (1951).
Treatment of the intact and broken out egg constituents with reducing chemicals was performed according to MacDonnell, Lineweaver and Feeney (1951). The determinations of the turbidities of diluted egg white solutions were performed as follows: The egg white was blended according to Sugihara et al. (1955) and thoroughly mixed with 5 volumes of distilled water. The mixture was allowed to stand approximately 5 minutes and turbidity then determined in a photoelectric colorimeter (Klett). The lysozyme employed in this work was prepared by direct crystallization from egg white and further purified by two recrystallizations and an isoelectric precipitation (Alderton and Fevold, 1946). It was dissolved in dilute acetic acid and then the pH of the solution was raised to 8.5 with sodium hydroxide before use. Conalbumin was prepared in crystalline form according to Feeney and Rhodes (1956). t RESULTS
Comparative deteriorations of chicken and duck eggs on incubation at 37° and 44° C: The changes in white and yolk indices in chicken and duck eggs were determined after storage at 37° and 44°C. Experiments were performed over a six-month period with small numbers of eggs from different sources. In all cases the duck eggs were found extremely resistant to deterioration at these temperatures as compared with the rapid changes observed in the chicken eggs. There was no detectable deterioration in the duck eggs at 37° and only a slight deterioration even after four days at 44°. Table 1 contains the data of five different experiments at 44°. The amounts and rates of deteriorations of chicken eggs were similar to those recently reported (Feeney, Weaver, Jones and Rhodes, 1956). Effect of storage of egg yolks in blended
Downloaded from http://ps.oxfordjournals.org/ at Uniwersytet Warszawski Biblioteka Uniwersytecka on May 22, 2015
(inhibition of hemagglutination caused by influenza virus and certain other viruses). A summarization of the comparative data of MacDonnell et al. (1954) and Sugihara et al. (1955) gives the following percentage composition on a dry weight basis for the chicken and duck egg whites respectively: lysozyme, 3.5 and 0.90; conalbumin, 12 and 2.8; ovomucoid, 11 and 15; cysteine (native), 0.46 and 0.30; cysteine (denatured), 0.60 and 0.32. The chicken egg white contained approximately 50% more virus antihemagglutinin activity. There are, of course, other differences in the poorly characterized components such as globulins and avidin, and Romanoff (1943) has reported differences in the physicochemical properties of the various layers of the egg white.
m
893
CHICKEN AND DUCK EGG DETERIORATION TABLE 1. —Deterioration
Exp.
of chicken and duck eggs
Chicken eggs1
Storage conditions
Duck eggs1
Indices Yolk
8.7 9.5
0.056 0.048
0.42 0.23
4 2
3 4
8.9 9.4
0.074 0.075
0.47 0.31
94 94
3 3
9.0 9.4
0.072 0.024
2 44 44
97 49 97
4 4 4
9.0 9.6 9.7
44 44
0 46 98
24 22 23
8.7 9.4 9.5
Temp.
Time
A
°C. 2 44
hr. 48 48
6 6
B
2 44
48 48
C
2 44
D
E
pH
Indices pH White
Yolk
8.7 9.5
0.074 0.083
0.45 0.41
6 6
9.0 9.4
0.078 0.082
0.40 0.36
0.44 0.16
2 3
9.0 9.4
0.057 0.053
0.40 0.37
0.062 0.051 0.027
0.42 0.23 0.14
4 4 4
8.9 9.5 9.6
0.079 0.072 0.061
0.46 0.40 0.38
0.064 0.043 <0.02
0.44 0.22 0.17
18
8.5
0.077
0.41
13
9.4
0.088
0.38
1
Values given for pH and indices are averages of data of numbers of eggs indicated. The five different experiments were performed over a period of four months.
•
white: Egg yolks of each species were separated aseptically from the whites and laced in bottles containing blended white of the same species and in other bottles containing white of the other species. In three separate experiments in which duck yolks were suspended in chicken egg white, little or no deterioration occurred under storage conditions which caused a rapid deterioration of chicken yolks (as measured by the change in yolk index). The results of one experiment in which the various combinations were studied are given in Table 2. Influence of reducing chemicals: Comparative studies were made on the influence of reducing chemicals (MacDonnell et al., 1951). In all cases closely parallel results were obtained with both the duck and chicken eggs and their components. Thioglycol caused thinning of the thick egg white, weakening of the yolk membrane and dissolution of preparations of yolk membranes of the eggs of both species in a similar manner. Effect oj ammonia: In contrast to the
nearly identical results with the two species given by reducing chemicals as described above, the effects of ammonia were radically different. As previously described by others (Almquist, Givens and Klose, 1934; Cotterill and Nordskog, 1954) exposure of intact shell eggs to ammonia gas caused decreases in the white index and increased translucence of the egg white. In the present studies decreases in the yolk indices were also obtained. There were, however, TABLE 2.—Deterioration of separated yolks stored in different blended whites1 Combinations
Yolk Indices 2
Yolk
White
Control 3
Stored4
Chicken Chicken
Chicken Duck
0.42 0.41
0.26 0.20
Duck Duck
Chicken Duck
0.41 0.38
0.38 0.36
1 Separated, combined and stored as described by Feeney el al. (1951). 2 Five replicates in each lot. 3 Controls measured 2 to 3 hours after combination. 4 Stored at 44°C. for 66 hours.
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White
No. eggs
No. eggs
894
M. B. RHODES AND R. E. FEENEY TABLE 3.—Effects
Chicken eggs1
Storage conditions Exp. NH82
+ B
0
+ C
0
+ 1 2
Duck eggs1
Indices
No. eggs
PH
White
Yolk
No. eggs
Indices PH
White
Yolk
°C. 2 37 37
hr. 24 24 24
6 6 6
9.1 9.1 9.5
0.055 0.046 0.037
0.42 0.37 0.30
6 8 8
9.2 9.1 9.5
0.062 0.057 0.064
0.41 0.38 0.38
37 37
24 24
6 6
9.2 9.5
0.055 0.038
0.41 0.34
8 8
9.2 9.5
0.073 0.077
0.41 0.42
2 2
24 24
6 6
8.9 9.6
0.063 0.066
0.42 0.40
Figures given for pH and indices are averages of data of number of eggs indicated. Ammonia gas added to desiccators as described in text. 0 = n o addition; -(- = addition.
no detectable differences in either the white with ammonia, other alkaline materials and or yolk indices in the duck eggs treated reducing chemicals markedly decreased the under similar conditions. Careful deter- turbidities obtained on dilution. Dilution in minations of changes in pH values of the solutions of relatively high salt concentraegg whites proved that the different results tion also decreased the turbidity. obtained with the chicken and duck eggs In Figure 1 are plotted the turbidities obwere not due to differences in final pH. The tained when blended chicken and duck egg data from three of a series of experiments white were mixed in various proportions on this subject are presented in Table 3. and then diluted with 5 volumes of water. Both chicken and duck egg yolks showed It is readily seen that the amount of turthe glossy effect described by Cotterill and bidity obtained is directly proportional to Nordskog (1954) for chicken eggs. the relative amount of chicken egg white Effect of dilution of egg white on forma- present in the mixture. tion of turbidity: The chicken and duck Influence of lysozyme on turbidity of egg whites differed extensively in the tur- duck egg white on dilution: Among the bidities obtained upon dilution in water. various differences between the whites of The procedure adopted for this study was the two species, one of more pertinence to rather similar to one of the older procedures the problem at hand was the difference in for the determination and separation of lysozyme content. It was knowledge of this crude ovomucin from egg white (Young, difference that made possible the prepara1937). Unblended chicken egg white gave tion of high-volume angel food cakes with a white web-like thick precipitate when duck egg whites through the addition of a mixed with S volumes of distilled water, small amount of lysozyme (MacDonnell, while duck egg white gave only a small Feeney, Hanson, Campbell and Sugihara, transparent gelatinous precipitate. When 19SS). the experiments were performed with Experiments were therefore performed in blended egg whites, chicken egg whites gave which crystalline lysozyme prepared from very turbid suspensions and the duck whites chicken egg white was added to duck egg only a slight opalescence. white and the influence of such additions Pre-treatment of the chicken egg white on the turbidities obtained on dilution were
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A
0 0
Temp. Time
of ammonia gas on chicken and duck eggs
CHICKEN AND DUCK EGG DETERIOKATION
FIG. 1. Influence of percentage composition of mixtures of chicken and duck white on the turbidity obtained on dilution in water. Turbidity was produced by dilution with 5 volumes of water as described in text.
studied (Figure 2). From the data of Figure 2 it is evident that the addition of very small amounts of lysozyme causes increases in the turbidities of duck egg whites upon dilution in water. No increases in turbidities were obtained by addition of conalbumin in amounts equivalent to the difference in the composition of duck and chicken white. DISCUSSION In the comparative studies of the storage stabilities of the chicken and duck eggs, a relatively high stability of the duck eggs was found in the resistance of the yolk membrane to deteriorative weakening as well as in the resistance of the thick egg white to thinning. A similar difference in the stability of both of the structures was
/ 2 3 f LYSOZYME ADDED Cmg/m/)
FIG. 2. Influence of addition of graded levels of lysozyme to duck white on the turbidity obtained on dilution in water. Turbidity was produced by dilution with 5 volumes of water as described in text. A blank consisting of equivalent amounts of lysozyme diluted in water was subtracted from each reading. (The blank reading subtracted was only 8-12 percent of the total.)
to have been anticipated from the proposal of Feeney et al. (1956) that the storage thinnings of the yolk membrane and thick white of the chicken egg have a similar basic mechanism. The chicken and duck eggs were found to differ in two other important respects: The chicken eggs showed deteriorations when exposed to ammonia gas and the chicken egg white produced a high turbidity on dilution in water. The duck eggs showed neither of these effects. The first of these differences might indicate a much greater lability of the principal structural component in chicken eggs to the alkalinity of the ammonium ion. Both of these differ-
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PERCENT, CHICKEN E66 WHITE , t'o go f« io 4 PERCENT PUCK 666 WHITE
895
896
M. B. RHODES AND R. E. FEENEY
duck egg white (MacDonnell et al., 1954) might be responsible for the resistance to a deteriorative mechanism involving reduction. On the other hand, the very low amount of lysozyme in the duck egg white might be responsible for resistance to a deteriorative mechanism involving changes in complexes of the proteins. The present data could be considered as more strongly supporting the theory involving the solubility of complexes. Many other aspects, however, remain to be investigated. Of major significance should be studies of the physical and chemical properties of the important constituents of duck egg white and analyses of the minor constituents such as anions, nucleic acids and globulins. Such studies on the comparative biochemistry should obviously be extended to include eggs of other avian species. SUMMARY AND CONCLUSIONS
In a study of the comparative proper" ties of chicken and duck eggs, the following results were obtained: 1. The duck eggs were much more resistant on storage to the deteriorative thinning of the thick egg white and weakening of the yolk membrane. In the case of the yolks, the chicken eggs deteriorated at least eight times faster than the duck eggs. 2. The egg white of one species did not influence the rate of breakdown of the yolk of the other species. 3. Reducing chemicals thinned the whites and yolk membranes of both species in a similar manner. 4. Duck egg white differed from chicken egg white in that blended duck egg white did not produce a high turbidity on dilution with water as was the case with chicken egg white. 5. Duck eggs differed from chicken eggs
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ences might indicate a difference in the type and extent of the interaction of constituents in complex formation. The possibility that lysozyme might be involved was strongly supported by the observations in which the addition of lysozyme to duck egg white caused turbidities on dilution similar to those obtained on dilution of chicken egg white. The apparent inertness of the duck egg white insofar as contributing to the turbidities of diluted mixtures with chicken egg white (or vice versa), however, suggested that both the reactivities and the stoichiometric relationships of the constituents should be considered. On the other hand, reducing chemicals had similar effects on the eggs of both species. This suggested a close similarity in the properties and composition of their important structural constituent (s). If one accepts the proposal of Feeney et al. (1956), that the deterioration of the yolk membrane and thick egg white have a similar basic mechanism, certain conclusions may be drawn from the results of the experiments in which the yolks were stored in the blended whites. The results with the duck egg yolks in chicken white might indicate that the chicken egg white does not contain an excess of a material which causes the deterioration (and which is diffusible). Likewise, the results with the chicken egg yolks in the duck white might indicate that the duck white does not contain an excess of an inhibitor or stabilizer (and which is diffusible). The results of the present study are in agreement with both of two possible theories for the mechanisms of storage thinning of egg white and yolk membrane: chemical reduction (MacDonnell et al., 1951) and, changes in solubility of complex structures (Hawthorne, 1950; Feeney et al., 1952; and Cotterill and Winter, 1955). The apparently low amount of sulfhydryl in
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CHICKEN AND DUCK EGG DETERIORATION
REFERENCES Alderton, G., and H. L. Fevold, 1946. Direct crystallization of lysozyme from egg white and some crystalline salts of lysozyme. J. Biol. Chem. 164:1-5. Almquist, H. J., J. W. Givens and A. Klose, 1934. Transmission of light by egg albumen. Ind. Eng. Chem. 26: 847. Bain, J. A., and H. F. Deutsch, 1947. The electrophoretic study of egg white proteins of various birds. J. Biol. Chem. 171: 531-541. Cotterill, O. J., and A. W. Nordskog, 1954. Influence of ammonia on egg white quality. Poultry Sci. 3 3 : 432-434. Cotterill, O. J., and A. R. Winter, 1955. Egg white lysozyme. 3. The effect of pH on the lysozyme-ovomucin interaction. Poultry Sci. 34: 679-686. Feeney, R. E., E. D. Ducay, R. B. Silva and L. R. MacDonnell, 1952. Chemistry of shell egg deterioration: The egg white proteins. Poultry Sci. 3 1 : 639-647. Feeney, R. E., and M. B. Rhodes, 1956. Prepa-
ration and antimicrobial activity of crystalline conalbumin. Federation Proc. 15: 249-250. Feeney, R. E., R. B. Silva and L. R. MacDonnell, 1951. Chemistry of shell egg deterioration: The deterioration of separated components. Poultry Sci. 30: 645-650. Feeney, R. E., J. M. Weaver, J. R. Jones and M. B. Rhodes, 1956. Studies of the kinetics and mechanism of yolk deterioration in shell eggs. Poultry Sci. 35: 1061-1066. Hawthorne, J. R., 1950. The action of egg white lysozyme on ovomucoid and ovomucin. Biochim. Biophys. Acta, 6: 28-35. Heiman, V., and J. S. Carver, 1936. The albumen index as a physical measurement of observed egg quality. U. S. Egg Poultry Mag. 42: 426429. MacDonnell, L. R., E. D. Ducay, T. F. Sugihara and R. E. Feeney, 1954. Proteins of chicken, duck, and turkey egg white. Biochim. Biophys. Acta, 13: 140. MacDonnell, L. R., R. E. Feeney, H. L. Hanson, A. Campbell and T. F. Sugihara, 1955. The functional properties of the egg white proteins. Food Tech. 9:49-53. MacDonnell, L. R., H. Lineweaver and R. E. Feeney, 1951. Chemistry of shell egg deterioration: The effects of reducing agents. Poultry Sci. 30: 856-863. Romanoff, A. L. 1943. Differentiation in layers of avian albumen. Food Res. 8: 286-291. Sugihara, T. F., L. R. MacDonnell, C. A. Knight and R. E. Feeney, 1955. Virus antihemagglutinin activity of avian egg components. Biochim. Biophys. Acta, 16: 404-409. Wolk, J., E. H. McNally and A. W. Brant, 1952. Yolk measurements used as an indicator of temperature deterioration of eggs. Poultry Sci. 31: 586-588. Young, E. G., 1937. On the separation and characterization of the proteins of egg white. J. Biol. Chem. 120: 1-9.
NEWS AND NOTES (Continued from page 870) in 1891 and obtained a B.S. degree at the University of Wisconsin in 1915. From 1915 to 1916 he served as Assistant Poultry Husbandman at Kansas State College, and from 1916 to 1917 as Instructor in Poultry Husbandry at the University of Wisconsin. In 1917 he joined the staff of the University of Nebraska.
He is a member of the Poultry Science Association, having served as Associate Editor of Poultry Science from 1933 to 1938 and the American Association for the Advancement of Science. Dr. John L. Adams will succeed him as Head of the Department. Professor Adams was born in Manitou, Oklahoma in 1921 and obtained a B.S.
(Continued on page 917)
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in that ammonia gas did not cause duck eggs to deteriorate rapidly as was the case with chicken eggs. Exposure of chicken eggs to ammonia gas resulted in an extensive decrease in the turbidity obtained on dilution of the white. 6. When chicken-egg-white lysozyme was added to duck egg white prior to dilution, duck egg white gave a high turbidity on dilution similar to chicken egg white. The significance of these findings in understanding the causes and mechanisms of deterioration of egg quality on storage was discussed.
897